The fibrous web saturator described herein relates to improvements in apparatus of the type disclosed in U.S. Pat. No. 1,595,474; U.S. Pat. No. 3,881,445; U.S. Pat. No. 3,644,137; U.S. Pat. No. 2,125,364; and U.S. Pat. No. 1,683,254 which generally disclose apparatus for vacuum treatment of fibrous web material. In the method of using the apparatus, the web is moved through a vacuum chamber to remove air which is held on the surface of the material or occluded in pores formed in the web of material. After passing from the vacuum chamber, the web is immersed in liquid in an effort to saturate the web.
Devices heretofore devised for vacuum treatment of a web moving through a vacuum chamber having encountered difficulties in sealing the chamber to permit reduction of pressure to a level sufficiently low to remove sustantially all of the air from the pores in the web so that they can be completely filled with coating material and the web saturated.
Apparatus similar to that disclosed in U.S. Pat. No. 3,881,445 has been used heretofore for applying an aqueous solution of various materials such as sodium silicate and starch to a paper web. The system, however, did not provide optimum saturation of the web at maximum web speeds.